CVE-2021-4330 in Envato Elements & Download and Template Kit Plugin
Summary
by MITRE • 03/07/2023
The Envato Elements & Download and Template Kit – Import plugins for WordPress are vulnerable to arbitrary file uploads due to insufficient validation of file type upon extracting uploaded Zip files in the installFreeTemplateKit and uploadTemplateKitZipFile functions. This makes it possible for attackers with contributor-lever permissions and above to upload arbitrary files and potentially gain remote code execution in versions up to and including 1.0.13 of Template Kit – Import and versions up to and including 2.0.10 of Envato Elements & Download.
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Analysis
by VulDB Data Team • 04/09/2026
The vulnerability identified as CVE-2021-4330 affects WordPress plugins Template Kit – Import and Envato Elements & Download, creating a critical security flaw that enables unauthorized file uploads. This vulnerability stems from inadequate input validation mechanisms within the file extraction processes of these plugins, specifically in the installFreeTemplateKit and uploadTemplateKitZipFile functions. The flaw allows attackers with contributor-level permissions or higher to bypass normal security restrictions and upload malicious files to the target WordPress installation. This represents a significant escalation of privileges issue since it transforms a low-privilege user account into a potential vector for more severe attacks including remote code execution.
The technical exploitation of this vulnerability follows a predictable pattern where an attacker uploads a malicious zip file containing arbitrary files that can be executed on the web server. The insufficient validation occurs during the extraction phase rather than at the initial upload stage, which means that even if the initial file upload appears legitimate, the extraction process fails to properly sanitize the contents of the zip archive. This type of vulnerability falls under CWE-434, which specifically addresses the improper restriction of file uploads, and represents a classic example of insecure file handling in web applications. The vulnerability's impact is particularly severe because it allows for remote code execution, enabling attackers to potentially take full control of the affected WordPress installation.
The operational impact of this vulnerability extends beyond simple file upload capabilities, as it creates a persistent threat vector that can be exploited repeatedly by attackers with contributor-level access. In a typical WordPress environment, contributor roles are often assigned to users who create and edit posts, but they should not have the ability to upload arbitrary files or execute code on the server. The vulnerability effectively undermines the principle of least privilege by allowing these users to escalate their privileges through malicious file uploads. This attack vector aligns with ATT&CK technique T1190, which describes the use of compromised accounts to establish persistence and execute malicious code, and T1078, which covers legitimate credentials use for unauthorized access. The vulnerability affects specific versions of the plugins, with Template Kit – Import being impacted up to version 1.0.13 and Envato Elements & Download up to version 2.0.10, making it crucial for administrators to verify their plugin versions and apply updates immediately.
Organizations should implement immediate mitigations including updating to the latest versions of the affected plugins where available, implementing additional file type validation at the web server level, and restricting file upload capabilities to only trusted user roles. Security measures should include monitoring for suspicious file uploads, implementing web application firewalls to detect malicious upload attempts, and conducting regular security audits of WordPress installations. The vulnerability demonstrates the critical importance of proper input validation and sanitization in web applications, particularly when handling user-supplied data such as file uploads. System administrators should also consider implementing network-level restrictions to limit access to plugin upload directories and ensure that all WordPress installations maintain current security patches and updates. The remediation process should include thorough testing of updated plugins to ensure compatibility while addressing the underlying security flaws that make such vulnerabilities possible.